Hi all, thanks in advance for your patience with this long post.

I've been researching wheel and tire sizes for my '67 Dart two door hardtop (not a post car). I have some questions about wheels and tires, not coming in without having read tons about this, but still I have some questions. Here's my car, fyi:

http://s785.photobucket.com/user/67dart ... y.jpg.html

It originally had 13" rims/tires and I've since moved up to 14" SBP stock rims. Great, now I've upgraded to 8.75 rearend and I'm ready to go to LBP wheels. I'll swap out the rear axles (currently SBP) and do a disc brake conversion up front to LBP.

OK, so as a first step, I have a set of 15" mopar cop car wheels, 7" width, and I'm measuring the back spacing. The distance from the mounting surface to the inner edge of the rim is 4.5" if I measure from the raised bead (red arrow) and 4.25" if I measure from the recessed area (green arrow).

http://s785.photobucket.com/user/67dart ... r.jpg.html

I looked at my rear brake drum (10 x 2.5") and it has a flat mounting surface. From this, I assume the bead area is the mounting surface on the rim and the backspacing is 4.5". Is that correct?

From what I've read, these mopar cop car rims will fit on my dart with say 215/60R15's or 225/60R15's (I've read many conflicting accounts of this, some say 215 is the largest you can go on the front of my car, others have reported much larger widths on the front, same year car...ugh). Any comments on that?

Finally, I see these rims as my intermediate set until I get to my final wheel choice, which I believe will be 17" rims, like these:

http://www.ebay.com/itm/17x7-17x8-inch- ... 1372967460

Here is an example of a '69 Dart with 17" rims, I think it looks great:
http://www.hotrod.com/cars/featured/mop ... e-dart-gt/
That blue car has 215/50R17 under the nose; 225/55R17 off the rear

The ebay ad says that the backspacing is 4" for the 7" wide rim, and 4.5" for the 8" wide rim (and 225's on the front and 245's on the rear). My question here is will these fit my Dart and if not, why not?

I had a discussion with Lou, and he suggests that the backspacing needs to be bigger to fit a 17" wheel on this car (unless one rolls their inner fender lip or cuts). I'm confused on this aspect of things. I realize there is also offset to consider, I'm just asking about backspacing assuming all things equal, why would the backspacing for a 17" rim need to be more than for a 15" rim?

Thanks all.

Brian

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Good thing they make more than one flavour of ice cream, because I think era-incorrect giant wheels like that look stuhoopid.

Keep in mind there are limits, lower than we'd like to imagine, on what these cars' steering linkages will tolerate in terms of wheel/tire mass and friction. The entire linkage was designed for really small tires on really small wheels with a really small road contact patch. Throw giant wheels and tires on the car, without doing a great deal of gussetting and other special custom reinforcment and upgrade work to the K-frame and steering linkage, and you're going to wear stuff out a lot faster. And not just replaceable stuff, but also stuff like the idler arm hole in the K-frame.

And then there's the suspension to think about: today's cars get away with giant wheels and tiny, super-stiff tire sidewalls because their suspensions are much more advanced. Throw that kind of combo at an A-body that has not been substantially (and expensively) custom-upgraded, and the car's ride will become highly unpleasant in a hurry...until you shake the car to pieces, then it won't matter any more.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I think really big wheels look stupid as well, 15's look good to me and the suspension was designed to handle those I suspect. 17's aren't that much bigger; I'm actually torn between 15's and 17's. The 15's give it that old school look, which is period appropriate. The 17's are right on the edge (for me) of being too big, but something about them I like. Maybe I'm really looking for 16's....Anyway, I definitely think 18's and larger are weird looking (I've seen them on Darts, wheel wells cut, larger tubs, etc just to cram them in there).

Back to my question though, all things being equal, width, offset; why would a 17" rim require more backset than a 15" wheel? The lateral points of contact, e.g. leaf springs, fender lip, frame, etc are the same distance from the wheel mounting surface, so I don't get it. I can see how vertical distance, a 17" tire being taller than a 15" tire might rub on the wheel well or something, but as to lateral clearance if both rims are e.g. 7" rims, same offset, seems like backspacing to fit for one should be OK fit with the other, no? What am I missing, somebody school me on this.

Brian

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You need to think in terms of offset rather than backspacing.

Your 17x7 with 4" backspacing and 17x8 with 4.5" have the same offset.


http://tires.tirerack.com/tires/Wheel%2 ... ackspacing

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I have had many different size and offset wheels on this car: 13", 14", and 15". The set up that is the best by far is the current one: 15x6" with 4" back space on front, and 15x7 with 4.25 back space on the rear.

15x7 all the way around was the second best. The narrower front wheels reduced over steer. Keep in mind I like the feel of the car with the rear sway bar. It tracks straighter with it. Wheels with either more or less backspace on the front caused loopy handling in tight turns. Changing the backspace did something unhealthy to the toe in as the turn got tighter.

The narrower cop car wheels are from an Aspen or Volare cop car, scored at a swap meet.

Sam

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I stuffed what I believe is the maximum (or nearly so) tire and wheel possible without cutting/bending under my '67 Valiant. 235/45R17 on 17x8" +28mm offset wheels up front and 255/40R17 on 17x9" +28mm wheels with 1" billet spacers in the back. You couldn't get your pinky finger between the leaf spring and tire, but they didn't rub. There are pictures around here somewhere, but I can't find them now as photobucket is blocked here at work.

I also had 1.04" torsion bars and good shocks. Grip was great, but all that grip exposed the horrible flex in the steering. It was as if there were a large spring in the system. You had to dial in extra steering input at the entry of a corner to compress the spring and then unwind the wheel a bit to keep a steady line through the corner. The 1967-only idler arm is bad, bad, bad for performance use.

On my '66 Dart I road raced I used 225/50R15 tires on 15x7" factory aluminum wheels off an R-body. Those, like the cop car wheels, are 1/4" positive offset/4.25" backspacing. They will probably look pretty silly unless the car is lowered.

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Joshua

I have run 14" and 15" wheels (7" wide) with 4" backspacing and never was happy with fitment. If you run 215 width tires, it will most likely be OK, but not much above that. 17" will be no different than 14" or 15".

If you buy wheels with 5" (or even more) backspace you can easily use spacers to space the wheels outward to where you want them.

If you are worried about old A-bodies and big tires (64 Dart, 64 and 66 Val and 68 Dart tested), then you will have minimal problems with durability and forces, as far as I have seen. I have not had a 67 car, though. Ask anyone who was at the Carlisle autoX this year how well my 64 Dart handles and how durable it is. I drove that car 3600 miles to OR with no issues after that. 17X8s with 32 mm offset and 225/45-17 tires. Have run as wide as 245s on Abodies with no issues.

Bottom line is that you have to measure everything yourself and check fitment and possibly use spacers to get things to line up perfectly. If you want a SAFE prescription requiring little or no measuring, then use 17X7" rims with 4.5-5" backspacing and 215 width tires in 45 or 50 aspect ratio.

Lou

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Home of Slant6-powered fun machines since 1988

No, wishfully thinking isn't the same as suspecting. It was designed for 13" × 4½" wheels and 6.50 × 13 tires under lightweight 106"-wheelbase '62 Valiants and Lancers with lightweight 170 or aluminum 225 engines. It was also used, without any upgrades, with 14" × 4½" wheels and with 14" × 5½" wheels and 7.00 × 14 tires under considerably heavier 111"-wheelbase '63-'72 Darts with heavier engines. You now propose to go much bigger/heavier with 15" wheels. The car won't fall apart in a week or a month or a year that way, but you will have greatly increased the loads and stresses on the whole (and hole) already-stressed-over--original-design-parameters system.

I've been awake 17 hours on 2½ hours' sleep; sorry, I'm being a blunt joik.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan, I consider you, among other things, my "spiritual" mopar guru, giving me the wisdom of chrysler designer's original intent. The keeper of the true mopar spirit...anyway, you get the idea.

That said, as I look at my spindles, ball joints, control arms, etc. they seem awfully heavy duty compared to newer cars, e.g., my 2009 CTS which has what looks like not as robust components but is sporting 235/45R18's all around. I realize when I assume anything, I may make an a _ _ out of myself, and perhaps the new cars use thinner materials but better placed/designed to handle more stress - but weren't the LBP pattern components designed to handle 15" wheels and tires easily? B and E body cars came with 15" tires as an option didn't they? Are you saying the frame etc, where all the same components bolt aren't as strong on the A bodies? I'm asking honestly, I don't know.

Brian

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Brian, My front suspension has all of the heavier components from the later A body. That includes idler arm, drag link, pitman, gear box and tie rods. This car feels tighter and more solid in its response to driver input than my 95 Corvette did. This after I added all possible stiffeners to the body of the Corvette.

Sam

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Sam, my cop car steelies are 15 x 7". You're saying 15 x 6" is better on the front for handling, that's interesting. I'll get to try 7" all the way around with the cop car wheels. Maybe if it feels weird for me as well, I'll go with 6" up front. That's helpful feedback.

I do have the firm feel roller bearing idler arm (73-76 type K frame) and sector support kit. I welded and gusseted my steering box mount before installing the K frame and I have a front sway bar on there. The handling is MUCH better than before. I don't have a rear sway bar, but my springs are pretty stiff (but softening a bit now, gladly), so I don't think I need one. I have a stock rebuilt steering box, maybe someday I'll splurge on a redhead or a .....borgeson...for anyone curious see: http://www.borgeson.com/xcart/home.php?cat=143

Dan, I can hear your mopar original intent blood starting to boil...the borgeson requires cutting the steering column shaft and installing a universal joint where the pot coupler once was. But it's 20 pounds lighter than a factory unit, there's more room for headers (or whatever) and (supposedly) you get the direct feel, no more play in your box.

Anyway, Dan, I believe you have talked me out of anything larger than 15" wheels, so there's that. I already have the right tranny speedo gear for those laying around here somewhere.

And thanks Lou for your helpful advice, I think I'll start with a set of 215's see where we go from there on the next set.

Brian

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You are welcome. If you do not drive in snow and are not a nutcase in the rain, these tires are amazing as an all around street tire. I would guess you could get 20-30k miles out of them, and fun miles.

Goodyear Eagle F1 Asymmetric 2 and 215/45-17 size would be perfect for your car.

http://www.tirerack.com/tires/tires.jsp ... mpare1=yes

Lou

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Home of Slant6-powered fun machines since 1988

They're not, and that can't be judged by eyeball.
The '73+ ball joints are heavier-duty than the '72-down items, but that doesn't address other parts already mentioned.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

That might've been good info to put earlier in the thread
...might be a nice upgrade. The pointless one that makes me roll my eyes is the Flaming River nonpower box, which is heavier and not better than a factory box.

My own pref in steering is a factory nonpower box built with a 20:1 worm assembly.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Sorry for not providing the later model suspension upgrades info in the beginning...

b

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